China is one of the world's largest emitters of greenhouse gases - some say it is already number one. But climate change is also having a huge impact in China, and nowhere more so than on the Tibetan plateau in the far west, thousands of metres above sea level.

Hang Maojia's family have seen Qinghai lake shrink over the years

Sometimes China can feel like several different countries - all crammed in behind one enormous border.

The province of Qinghai is a land of snow-capped mountains and glaciers, deserts and vast open grasslands. A world away from the big cities of Beijing and Shanghai.

It has a fragile ecosystem - susceptible to the slightest change in climate - and scientists say global warming is already having a major impact here.

The first stop on my journey is the clear waters of Qinghai lake.

It is one of the largest lakes in China, stretching far off into the distance, surrounded by hills and mountains and the bright blue sky beyond.

It seems as though nothing has changed here for hundreds, possibly thousands of years - but locals tell a very different story.

Hang Maojia is 23 and has lived here all her life. "When my mother was young the lake used to be here," she told me, indicating a point some 300m (984ft) from the water.

Scientists and environmentalists say global warming is partly to blame for this dramatic drop in water levels. Rising temperatures mean that the waters are evaporating faster than in the past.

Wake-up call

Leave Qinghai lake behind and drive further west and you come to the Gobi desert - an arid landscape of rocks and sand under a baking hot sun.

It's getting warmer in the summer and colder in the winter. It should be summer now but it snowed just a few days ago

Resident Deng Wanhua

Deserts cover large parts of northern China. Scientists are worried that they are growing at a faster rate than ever before - mainly because of climate change.

The village of Nuomuhong is just two rows of houses sitting in the middle of the desert. The lorries pass through on their way to somewhere else. But those who live here have noticed changes in the weather, like 67-year-old Mrs Jiang.

"It has been getting hotter and hotter in recent years," she told me. "Our water supply has slowly been drying up. Without that it will be impossible to live here."

Higher up above the Gobi desert is the village of Xidatan. It is 4,000m (13,123ft) above sea level. The desert has given way to mountains covered in a thick layer of snow.

Xidatan is a ramshackle line of low brick houses that stand silent - many in ruins. It is not easy to survive at this level and conditions are getting harder.

Local resident Deng Wanhua tells me that the weather is now completely unpredictable. "It's getting warmer in the summer and colder in the winter," she says. "It should be summer now but it snowed just a few days ago."

And close to the village, another sign of changing weather patterns. The glaciers that have been here for thousands of years are melting.

How long will this Tibetan plateau landscape last?

And that is happening right across the Tibetan plateau.

Melting waters from the glaciers feed many of Asia's longest rivers, including the Yangtze and the Mekong.

If the glaciers disappear, that could have a huge impact on hundreds of millions of people downstream.

I came to the end of my journey 5,000m (16,404ft) above sea level in the Tangula pass on one of the highest roads in China.

On my trip I had seen the impact of climate change at first hand.

What is happening in Qinghai is a wake-up call about the long term impact of global warming - not just for China but for much of Asia as well.